I live in Berlin. I have worked, freelanced, and started a company here. Getting a self employment visa if you are in technology is very, very easy, as is finding full-time work if that's what you're after.

My current permit allows me to stay for four years, with indefinite extension so long as I'm doing work in tech.

Starting a company is about on par with the U.S. (I also incorporated in Delaware as a foreigner). There's some beaurocracy where knowledge of the language and the required forms, or else friends to help, is very necessary. Taxes are much simpler, payroll is a little more complicated than in the U.S.